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Thread: fridge tripping electricity safety switch?

  1. #21
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    7AM and all is well



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    Years ago we had trouble at work with a hefty circuit breaker that used to POP under certain conditions when a Hecla Brand stainless steel kettle began to boil.
    I found this generally happened only when the room heater (oil) was running and the room was fairly hot.
    The circuit breaker board was mounted high on one wall near the low ceiling (8 foot) and was the hottest area due to the natural air draft of the room.
    This was long before those RCD switches were ever thought of but after several experiments, this only 'popped' as the Kettle reached Boiling point and the air was hot around the board.

    Its a shame you cant bypass the RCD because along with the others, I think its most likely at fault.
    I stand unequivicably behind everything I say , I just dont ever remember saying it !!

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    Quote Originally Posted by Manwhore View Post
    it means in spite of the weird RCD tripping problem, the fridge is performing exactly as it should.
    Hate to state the obvious, but if your fridge is the cause of the RCD breaker tripping, then it is not performing exactly as it should.

    So, from all the information you've been given, you still can't figure out why your fridge might run "exactly as it should" for a while, then trip the RCD?

    Quote Originally Posted by Manwhore View Post
    I dont know if you realize it, but thats valuable information when trying to find a fault.
    Thanks for the tip.

    When you finally figure out what the real problem is, please let us know.

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    First of all do you have 1 RCD for all the circuits in the house or a RCD for each circuit,
    and looking at the RCD can you tell if the RCD is tripping out due to a earth leakage problem or an over current problem?

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    Quote Originally Posted by typan View Post
    and looking at the RCD can you tell if the RCD is tripping out due to a earth leakage problem or an over current problem?
    OK, now you've got me curious. How does one tell if a combined RCD/MCB trips out from overload, or Earth-leakage?

    BTW, the OP has one large RCD for all his power circuits. An easy way of bringing an older installation up to spec. A bit harder to fault-find though.

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    One RCD for all your power circuits is a cheap way of brining an old installation up to spec. What you find in that type of installation is all of the circuits will add it's own earth leakage to that one RCD, eg. circuit 1 may leak say 10mA circuit 2 may leak say 10mA and circuit 3 may leak 15mA which is all fine but it adds up to a total of 35mA on one RCD so the RCD will trip, it's doing it's job and you will fine the RCD should trip around 30mA or BUT less NOT MORE THAN 30mA BY LAW. Some RCD will show if it has tripped by earth leakage or over current.

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    I swear, there must be serious differences between RCD's.
    I've had some, and I swear they are not as sensitive as they should, and others that struggle to stay on with a kettle boiling water.
    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!

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    the SAA wiring rules state that an RCD MUST trip <30mA BUT not over 30mA within a time frame I forget what that time frame is and in hospitals <10mA max trip RCD's are used.

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    Yeah, when i test them with a dummy fault load, they generally all trip at 25mA.
    Time frame is another matter.

    The OP could probably solve his issues by replacing the CB the fridge is on, for a combo 1pole rcd/mcb, to give some extra headroom on fault current.
    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!

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    I do have 1 RCD covering all circuits.

    As I was looking around online, Ive found its common practice to leave 1 power point off the RCD in the kitchen for the refrigerator freezer, the defrost seem to trip RCDs quite a lot.

    The good news is whatever was tripping my RCD seems to have stopped, for now.

    Many thanks to all those who offered advice
    Last edited by Manwhore; 05-12-15 at 04:52 PM.

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    Quote Originally Posted by Manwhore View Post

    As I was looking around online, Ive fond its common practice to leave 1 power point off the RCD in the kitchen for the refrigerator freezer, the defrost seem to trip RCDs quite a lot.
    It was, and its a been a loooong time since you were allowed too.
    We used to do the same for circuits than ran outdoor water pumps or submersible pumps.
    All must be on protected circuits these days.
    I guess, you could make your fridge "fixed" wiring, by chopping the plug top off and fitting an isolation switch, then you would be exempt from the RCD rule.
    Last edited by oceanboy; 05-12-15 at 02:57 PM.
    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!

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    Quote Originally Posted by Onefella View Post
    An easy way of bringing an older installation up to spec. A bit harder to fault-find though.
    Quote Originally Posted by typan View Post
    One RCD for all your power circuits is a cheap way of brining an old installation up to spec.
    Nice to see you're reading everyone else's posts.

    Quote Originally Posted by mtv View Post
    It may be a cyclic defrost
    Quote Originally Posted by nomeat View Post
    If it trips in the defrost cycle then it could mean that the heating element is faulty and it has a closed or intermittent contact to earth.
    Quote Originally Posted by Onefella View Post
    Auto-defrost uses a heating element on the evaporator coils, and uses a timer to run through the cycle once a day. Heating elements are notorious for Earth-leakage
    Quote Originally Posted by gulliver View Post
    All automatic defrost have a Timer. So it could happen at the same time.
    Quote Originally Posted by Manwhore View Post
    As I was looking around online, Ive found its common practice to leave 1 power point off the RCD in the kitchen for the refrigerator freezer, the defrost seem to trip RCDs quite a lot.
    No need to 'look around online' mate. You had all the info right here.

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    I'd be using an insulation resistance tester ('Megger') to find the culprit in a case like this. I expect the earth leakage on something is borderline bad occasionally spiking high enough to trip the RCD, I had a similar situation here that turned out to be the MOV in a surge protected power board breaking down at normal voltage levels.

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    Sorry for resurrecting an old post, but if you identify the problem to be related to a leaking defrost heater coil, can you disconnect it and still keep running the fridge? I know that ice will build up, but will give us some time to buy a new fridge/ or new coil?

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    Quote Originally Posted by JK200SX View Post
    Sorry for resurrecting an old post, but if you identify the problem to be related to a leaking defrost heater coil, can you disconnect it and still keep running the fridge? I know that ice will build up, but will give us some time to buy a new fridge/ or new coil?
    No problems running the fridge. Just defrost manually.

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    Quote Originally Posted by JK200SX View Post
    Sorry for resurrecting an old post, but if you identify the problem to be related to a leaking defrost heater coil, can you disconnect it and still keep running the fridge? I know that ice will build up, but will give us some time to buy a new fridge/ or new coil?
    This is what I would do to diagnose the heater element suspected of tripping out the RCD without using test equipment.

    Cheers.

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    Cemented tube type heating elements are notorious for moisture ingress which lowers the insulation resistance between the element in the centre of the tube and the outer metal tube which is earthed. Ovens, frypans, radiant coil hotplates, kettles, defrosters etc all use these types of heating elements. They can be dried out by running them on a non-RCD protected circuit or even blasting them with a blowtorch if removed from the appliance.

    My house was built in the 90s and has an oven circuit which is not covered by the RCD for this reason (risk of occasional false tripping). Never had a problem with the fridges or freezer though (RCD circuit) but they've never been left out of service either
    Last edited by Skepticist; 13-01-19 at 09:21 PM.

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